Non-sustainable industrial practices aren’t something that’s exclusive to modern societies. New research from Tel Aviv University showcases how an ancient copper processing site in the Timna Valley led to the degradation of the local environment.

The findings are based on samples of charcoal used as fuel for copper-processing furnaces in Israel’s Timna Valley during the 11th to 9th centuries BCE. The research showed that the charcoal fuels used here changed over time. Earlier samples were produced from high-quality local wood (white broom and acacia thorn trees) but their quality decreased over time, with later samples being produced from low-quality wood fuel and timber imported into the area.

What does all of this mean? Well, the team explains that the progressive drop in the quality of wood used to fuel copper-smelting furnaces in this area suggests that local resources were not managed in a sustainable manner. This is further supported by the discovery of foreign, imported wood species, a development which suggests that local resources were starting to deplete by this point.

Industrial degradation

“Our findings indicate that the ancient copper industry at Timna was not managed in a sustainable manner, with overexploitation of local vegetation eventually leading to the disappearance of both the plants and the industry. Copper production was not renewed in this region until about a thousand years later, and the local environment has not recovered fully to this day,” says the researchers.

Prof. Erez Ben-Yosef, director of the archaeological excavations in the Timna Valley and co-author of the paper describing the findings, explains that a vast copper industry developed in the Timna Valley for about 250 years between the 11th and 9th centuries BCE. Thousands of mining sites in the area fed ore to the furnaces of about 10 processing sites in the valley.

This site was so significant that it was also mentioned in the Bible, which recounts that King David conquered the area of Timna (known at the time as Edom) and that his son Solomon used copper from this area to build the Temple in Jerusalem. The site is still known today as ‘King Solomon’s Mines’.

“We can only assume that David took an interest in this remote desert region because of its copper—an important and valuable metal at the time, used for making bronze among other purposes. The Timna copper industry was run by the local Edomites, who specialized in this profession, and copper from Timna was exported to distant lands, including Egypt, Lebanon, and even Greece. This study shows, however, that the industry was not sustainable, a fact that may fit in well with occupation by a foreign power, perhaps ruled from Jerusalem.”

The processing techniques used at Timna were highly advanced for their time, the authors explain. Copper ore in the area was smelted in temporary earthenware furnaces at temperatures in excess of 1,200 degrees Celsius for about eight hours. After cooling down enough, the furnaces were smashed and a lump of refined copper metal was retrieved from the base.

Wood charcoal was the fuel used to allow furnaces to reach the required temperatures. This material was prepared at specialized sites beforehand through slow, oxygen-deprived combustion of wooden mass from trees or bushes.

That being said, vegetation today is extremely sparse in the Timna Valley, which raises the question: where did all of that wood come from? In order to find out, the team collected samples of charcoal from the smelting sites and studied their structure in the lab. The samples were obtained from mounds of industrial waste at two sites in the Timna Valley. The dry, desert conditions here allowed the charcoal to remain relatively intact over the millennia.

Roughly 1,000 samples were brought to a laboratory at Tel Aviv University that specializes in the analysis of plant remains from archeological digs, where they were examined using an electron microscope. This allowed the researchers to determine the species of plant from which the charcoal was made. Each sample was dated according to the layer of the waste mounds in which they were found, and some were also sent for carbon-14 dating to ensure that the team’s estimations were accurate.

All in all, the team reports finding “significant changes in the composition of the charcoal” over time. Samples from the bottom layer of the mounds (dated to the 11th century BCE) were produced mostly from acacia thorn trees (40%) and white broom, including broom roots (40%). These are both known as being high-quality fuel, with the ‘burning coals of the broom tree’ even being mentioned in the Bible as good firewood.

About 100 years later, however, the composition of charcoals at Timna began to change. Wood of inferior qualities, including desert bushes and palm tree wood, was more and more commonly seen in the charcoal. Later still, imported wood also started showing up in the charcoal samples, including terebinth brought in from dozens of kilometers away and junipers originating from over 100km away in the Edomite plateau in present-day Jordan.

This gradual change in the quality of fuel used at the site was likely the product of an unsustainable exploitation of local wood resources. High-quality firewood species like acacia and white broom were not allowed to replenish, and eventually, their numbers dwindled so much that other sources of wood needed to be exploited. Eventually, these too would be depleted, at which point the Timna smelteries started relying on imports of firewood.

“Based on the amount of industrial waste found at the processing sites we can calculate the quantity of woody plants required for producing copper,” says Prof. Ben-Yosef. “For example, the production site called the ‘Slaves’ Hill,’ which was only one of several sites operating simultaneously, burned as many as 400 acacias and 1,800 brooms every year.”

“As these resources dwindled, the industry looked for other solutions, as evidenced by the changing composition of the charcoal. However, transporting woody plants from afar did not prove cost-effective for the long run, and eventually, during the 9th century BCE, all production sites were shut down. The copper industry in the Timna Valley was renewed only 1,000 later, by the Nabateans.”

The study finds some of the earliest-seen signs of industry-driven environmental damage. This was caused primarily by overexploitation of key species in local ecosystems, which helped support many other species, stabilized soils, and retained water. The disappearance of these species led to a cascading effect that permanently damaged the area.

According to the authors, local ecosystems have not yet recovered from the damage caused by the Timna Valley smelters; what we see today in areas like Israel is not how these areas naturally developed. Species like the white broom, which were once abundant in the Timna Valley, are now extremely rare. Others have disappeared completely, the team explains.

The findings showcase just how far-ranging the effects of man-made ecological damage can become. The Timna Valley smelteries represented an industrial pursuit that was orders of magnitude less intensive than the industries of today. And although our technology and know-how allow for much greater developed and efficient production today, we would best pay heed to the story of the Timna Valley and how similar processes can unfold today.

The paper “Fuel exploitation and environmental degradation at the Iron Age copper industry of the Timna Valley, southern Israel” has been published in the journal Scientific Reports.